From mboxrd@z Thu Jan  1 00:00:00 1970
From: Florian Westphal <fw@strlen.de>
Subject: Re: Non-Understood Message
Date: Tue, 13 Nov 2012 23:53:31 +0100
Message-ID: <20121113225331.GG20678@breakpoint.cc>
References: <50A2A40E.5050802@cats-muvva.net>
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Cc: netfilter-devel@vger.kernel.org
To: Nicole <nicole@cats-muvva.net>
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Nicole <nicole@cats-muvva.net> wrote:
> MYTARGET.0 target: invalid size 65540 (kernel) != (user) 4

[..]

> struct xt_mytarget_tginfo {
>     __u8    value;
> 
>     __u8    mode;
> 
>     bool    final;
> 
>     bool    set_value;
> 
>     __u8    by_port[USHRT_MAX];
> };

Its too large.  The kernel <-> userspace abi encodes size
in 'u16' datatype, thus the target size sent by userspace overflows.